Publishing companies Roc and Ace
 

Is one a subsidary of the other? The reason I ask is that I just finished an ace book that was released on Tues., and the about the author reads:
"Simon R Green, who began his career with Ace quite a few years ago, is now a bestselling author for ROC."

Seems to be a contradictory statement, although it could be a typo, as I know in the past he's published for ROC. However, the website for ROC is penguinputnam.com and Aces is penguin.com.

Someone make sense of this for me pretty please?